Washington: Crabs, insects and spiders, hit by the huge 2010 oil spill from the rig Deepwater Horizon, surprisingly recovered within a year if their host plants remained healthy, a study reveals.

Brittany McCall, University of Houston graduate student and biology professor Steven Pennings, her adviser, sampled arthropods and marine invertebrates in coastal salt marshes at the time of the oil spill in the Gulf of Mexico, as well as a year later.

Both of them gathered samples in areas where relatively low levels of oil were present but the plants still appeared healthy and undamaged, the journal Public Library of Science ONE reported.

They found that in these areas, the numbers of crabs, insects and spiders were reduced by up to 50 percent because of the oil exposure, according to a university statement.

"This study demonstrates that appearances can be deceiving," Pennings said. "Arthropods are quite vulnerable to oil exposure. These results are very important because they show that we can`t assume that the marsh is healthy just because the plants are still alive."

However, the fact that some plant life remained intact in these areas apparently was key to how the arthropods recovered.

When the Houston researchers sampled the same areas a year later, all three groups appeared to have recovered, suggesting that arthropods affected by oil may recover if their host plants remain healthy.

"Salt marshes are commonly disturbed by natural events and, as a result, they may be able to also recover from oil spills if the oil disturbance is not too large," Pennings said.